Manufacturing of semiconductor devices typically involves performing a sequence of procedures with respect to a substrate or “wafer” such as a silicon substrate, a glass plate, etc. These steps may include polishing, deposition, etching, photolithography, heat treatment, and so forth. Usually a number of different processing steps may be performed in a single processing system or “tool” which includes a plurality of processing chambers. However, it is generally the case that other processes are performed at other processing locations within a fabrication facility, and it is accordingly necessary that substrates be transported within the fabrication facility from one processing location to another. Depending on the type of semiconductor device to be manufactured, there may be a relatively large number of processing steps employed, to be performed at many different processing locations within the fabrication facility.
It is conventional to transport substrates from one processing location to another within substrate carriers such as sealed pods, cassettes, containers and so forth. It is also conventional to employ automated substrate carrier transport devices, such as automatic guided vehicles, overhead transport systems, substrate carrier handling robots, etc., to move substrate carriers from location to location within the fabrication facility or to transfer substrate carriers from or to a substrate carrier transport device.
Such transport of substrates typically involves exposing the substrates to room air, or at least to non-vacuum conditions. Either may expose the substrates to an undesirable environment (e.g., oxidizing species) and/or contaminants.